通过阴极发光干涉术揭示电介质和等离子体结构中光激发的时间特性
Revealing time characteristics of optical excitations in dielectric and plasmonic structures through cathodoluminescence interferometry
AI总结：
本研究开发CL干涉术，通过傅里叶变换分析CL干涉图获取光学共振时间特性，经多种纳米结构实验验证，实现纳米级测量的飞秒级分辨率光谱、空间与相位信息获取。
AI中文摘要：
阴极发光（CL）光谱学可实现纳米级空间分辨率的光激发探测，但光学共振的直接时间分辨测量仍具挑战性。本研究证明，CL干涉术无需超快泵浦-探测方案即可获取纳米级共振散射体的时间响应、相位行为及模式光谱结构。我们建立了分析框架，其中对角度和频率分辨的CL干涉图进行傅里叶变换，可得到由线性光学响应决定的光学共振衰减时间。多模式共振器表现出与光谱模式分裂相关的特征时间CL拍频信号。通过利用附近金属表面发射的过渡辐射作为宽带参考，我们进一步实现了相位检索以及瞬时发射与共振发射过程之间的互相关测量。对金纳米颗粒、宽带等离子体发射器、金纳米星和支持多极米氏共振的硅纳米球的实验测量证实了理论预测，每个体系的衰减时间在1-10飞秒范围内。本研究结果确立了CL干涉术作为一种强大方法，可在单次纳米级测量中获取光谱、空间和相位信息，且具有飞秒级分辨率。
英文摘要：
Cathodoluminescence (CL) spectroscopy provides access to optical excitations with nanometer spatial resolution, but direct time-resolved measurements of optical resonances remain challenging. Here, we demonstrate that CL interferometry provides access to the temporal response, phase behavior, and modal spectral structure of resonant nanoscale scatterers without requiring ultrafast pump-probe schemes. We develop an analytical framework in which Fourier transformation angle- and frequency-resolved CL interferograms yields the decay time of optical resonances governed by the linear optical response. Multimode resonators exhibit characteristic temporal CL beating signatures associated with spectral mode splitting. By exploiting transition radiation emitted from a nearby metallic surface as a broadband reference, we further demonstrate phase retrieval and cross-correlation measurements between instantaneous and resonant emission processes. Experimental measurements on Au nanoparticles, broadband plasmonic emitters, Au nanostars, and Si nanospheres supporting multipolar Mie resonances confirm the theoretical predictions, and decay times in the range 1-10 fs are derived for each system. Our results establish CL interferometry as a powerful approach for accessing spectral, spatial, and phase information within a single nanoscale measurement with fs resolution.
